Serum osteocalcin (BGP) levels in normal men: a longitudinal evaluation reveals an age-associated increase.

Serum levels of bone gla protein (BGP) have been reported to increase with aging and hence to reflect an age-related increase in bone remodeling activity. To evaluate the relationship between aging and serum BGP levels in a study of longitudinal design, we measured BGP concentrations in 77 normal men at 6 month intervals over a 3 year period. Mean BGP levels at the onset (4.95 +/- 1.5 ng/ml) increased significantly during the study (p = 0.004), and the mean of individual BGP slopes was positive (0.38 +/- 0.6 ng/ml per year, p = 0.0001). The rate of change in BGP was not related to serum creatinine levels or dietary calcium intake.